HIGH PRESSURE PUMP,ESPECIALLY FOR A FUEL INJECTION DEVICE IN AN INTERNAL COMBUSTION ENGINE

Abstract

The high-pressure pumps display a pump casing (10, 12, 14) in which several pump elements (16) are located, whereby fluid is fed under high pressure through the pump elements (16) via a high-pressure duct system to a common high-pressure connector (42). The pump casing has a casing body (10) and a casing lid (14) for every pump element (16) that covers the same and is connected with the casing body (10). The high-pressure duct system in the casing body (10) displays intersection-free, running high-pressure wells (52, 54), which merge in the area of transition from the casing body (10) to one of the casing lids (14a) or in one of the casing lids (14a) at a common high-pressure connector (42).

Full Text

High-pressure pumps, meant particularly for a Fuel Injection Device Of an Internal Combustion Engine
Prior Art
The invention emanates from a high-pressure pump, meant particularly for a fuel injection device of an internal combustion engine according to the genre of Claim 1.
This type of high-pressure pump is established through DE 198 02 476 A1. This high-pressure pump displays a pump casing in which several pump elements are located. Fuel is fed through the pump elements to a common high-pressure connection via a high-pressure duct system. The pump casing of the high- pressure pump is thereby designed as a single unit and the high-pressure duct system has high-pressure wells that run through the pump casing and end in one another, thereby creating intersections. High pressures, such as those required in fuel injection devices for the attainment of higher efficiency and lower toxic emission as in the case of internal combustion engines, subject the pump casing to great load. A high-pressure well intersection results in stress peaks in the pump casing in accordance with which the pump casing has to be dimensioned and has to be constructed with regard to the material. A cost-intensive hardness treatment for the pump casing is hereby also required. Manufacture of the high- pressure pump is, therefore, expensive due to these reasons.
Advantages of the Invention
The high-pressure pump according to the present invention, with characteristics in accordance with Claim 1 has the advantage, when compared to the latter, of being less exposed to stress due to the absence of intersections and can thus be manufactured from a cost-effective material and in a simpler manner whereby the overall manufacture of the high-pressure pump is more cost-effective. Bores with intersections customarily exist in casing lids, therefore requiring the same to anyway be manufactured from a material with the corresponding resistance and further intersections of the high-pressure wells occurring there, do not result in any increased expenditure.
Beneficial designs and other details of the high-pressure pump according to the present invention are provided in the dependent claims.
Drawing
Two exemplary embodiments of the invention are illustrated in the drawing and explained in greater detail in the following description. Figure 1 represents a longitudinal section of the high-pressure pump. Figure 2 represents a cross- section of the high-pressure pump along line II - II in Figure 1 in accordance with a first exemplary embodiment and Figure 3 illustrates a cross-section of the high- pressure pump in accordance with the second exemplary embodiment.
Description of the Exemplary Embodiment
A high-pressure pump, particularly one meant for a fuel injection device of an internal combustion engine, a motor vehicle for example, is illustrated in Figures 1 to 3. Fuel is thereby fed through the high-pressure pump under up to 2000 bar high-pressure system, for example, into a repository from which fuel is drawn for the purpose of injection into the internal combustion engine. The high-pressure pump has a pump casing made of several parts of which the casing body 10, a flange 12 and a casing lid 14 that is connected to the casing body 10 are a part. Several pump elements 16 are located in the pump casing, for example three equally distributed pump elements 16 above the periphery. A pivoted drive shaft 18 is located in the casing body 10 and in the flange 12 through which the pump elements 16 are driven. The drive shaft 18 is pivoted through a bearing point 20 in the casing body 10 and through a bearing point 22 in the flange 12 around an axle 19 and is powered by the internal combustion engine, in a manner not illustrated in the figure. The drive shaft 18 has an eccentric cam 24 on which a hoisting ring 26 is supported. Pump elements 16 respectively display a pump plunger 28, which lies in a cylinder bore 30 that can be relocated close to the drive shaft 18 in an at least approximately radial manner. The cylinder bores 30 of the pump elements 16 can be designed in the casing body 10 or in the casing lids 14. A casing lid 14 that covers outwards is foreseen for every pump element 16 and is radial to the rotation of the axis 19 of the drive shaft 18 with regard to the pump elements 16. The pump plunger 28 of every pump element 16 supports itself at the hoisting ring 26 with its plunger foot 29, whereby the plunger foot 29 is held in contact with the hoisting ring 26 through a spring 32 that supports itself on the one hand at the casing body 10 or the casing lid 14 and on the other hand at the piston foot 29.
Through the pump plungers 28 of every pump element 16, a pumping chamber 34 is restricted in the cylinder bore 30 in each case by its front side. The pumping chamber 34 can be connected to a fuel supply channel 38, in which low pressure prevails, by an inlet valve 36 opening out into the pumping chamber 34. Apart from this, the pumping chamber 34 can be connected through an outlet valve 40 opening out into the repository through a high pressure duct system running in the casing body 10 and in the casing lid 14, described later in greater detail, to the repository. Through the rotation of the drive shaft 18, the pump plungers 28 are driven through the eccentric cam 24 and the hoisting ring 26 in a lifting motion. When the respective pump plunger 28 moves radially inwards, the same will implement an intake stroke, whereby the respective inlet valve 36 gets opened so that the fuel flows in through the fuel supply channel 38 to the respective pumping chamber 34 while the respective outlet valve 40 is closed. When the respective pump plunger 28 moves radially outwards, this then executes a discharge stroke whereby the respective inlet valve 36 is closed and the compressed fuel moves under high pressure into the repository through the opened outlet valve 40 via the high-pressure duct system.
A high-pressure connector 42 is located at a casing lid 14a to which a high- pressure line 44 leading to the repository is connected. Fuel fed from the pump elements 16 is led through the high-pressure duct system to the high-pressure connector 42 common to all pump elements 16. The high-pressure connector 42 can be located with any orientation at the casing lid 14a. The respective inlet valve 36 and/or the respective outlet valve 40 of each pump element 16 can be located in the respective casing lid 14a, b, c.
The high-pressure duct system in the casing body 10 and in the casing lid 14a, b, and c will be explained in greater detail subsequently with the help of Figure 2. In both casing lids 14b, c where the high-pressure connector 42 is not located a bore 50 is located subsequent to the respective outlet valve 40 leading away to the casing body 10. The bores 50 run at least approximately radially to the rotating axis 19 of the drive shaft 18. The ports of the bores 50 can be expanded in diameter, for example conically or in the shape of a sphere. The casing lids 14a, b, c and the casing body 10 have surfaces 11 and 15 respectively that face each other and are at least approximately level surfaces with which these come into contact. High-pressure wells 52 and 54 run in the casing body 10 that are connected respectively to the bores 50 of the two casing lids 14b, c and lead to the casing lid 14a at which the common high-pressure connector 42 is located. At the surfaces 15 facing the casing lids 14b, c of the casing body 10, a recess 56 is inserted at whose at least approximately level floor 57 the high-pressure wells 52 and 54 respectively end. The port of the high-pressure wells 52 and 54 respectively at the floor 57 of the recess 56 is preferably rounded in each case. This can take place with a form bore that can be attached to the level floor 57 of the recess 56. The recesses 56 respectively display a larger cross-section than the high-pressure wells 52, 54. In the recesses 56, a surrounding sealing ring 58 is inserted respectively in the high-pressure wells 52, 54 through which the transition from the bore 50 in the casing lid s 14b, c to the high-pressure well 52 and 54 respectively in the casing body 10 gets sealed.
In the first exemplary embodiment illustrated in Figure 2, a recess is inserted in the surfaces 11 of the casing body 10 facing the casing lid 14a, which displays an at least approximately level floor 61. The two high-pressure wells 52 and 54 in the casing body 10 end in the recess 60 at a distance from one another. The recess 60 is thus larger in cross-section than the sum of the diameter of both high-pressure wells 52, 54. The port of the high-pressure wells 52, 54 at the floor 61 of the recess 60 is preferably rounded in each case, that in turn can be easily manufactured with the help of a form bore that is capable of being put at the level floor 61 of the recess 60. A sealing ring 62 surrounding the high-pressure wells 52, 54 is inserted in the recess 60. A bore 50 is inserted in the casing lid 14a that is located at least approximately central to the recess 60 and this bore 50 leads to the common high-pressure connector 42. The bore 50 runs at least approximately radially to the rotating axis 19 of the drive shaft 18. The port of the bore 50 that faces the recess 60 can be widened in diameter, for example, conically or rounded. The sealing ring 62 seals the transition from the high- pressure wells 52, 54 in the casing body 10 to the bore 50 in the casing lid 14a. The bore 60 in the casing lid 14a and the outflow of the outlet valve 40 located in the casing ring 14a leads to the common high-pressure connector 42. The high- pressure wells 52, 54 run in the casing body 10 without intersections and are merged in the recess 60 at the transition area from the casing body 10 to the casing lid 14a. The operational demands on the casing body 10 are thereby kept to the minimum so that the same can be manufactured from a cost-effective metal with sufficient resistance and without requiring special hardness treatment as, for example, in the case of steel or in the case of lower pressure created by the pump elements 16, also made from a light metal such as, for example, aluminium. Alternatively, if a metal possessing a high resistance is used such as is required when running the high-pressure wells with intersections, the pressure created through the high-pressure pumps can be increased, in spite of which a satisfactory durability of the casing body can be guaranteed. The casing lids 14a, b, c have intersections at the transition of the outflow of the respective outlet valves 40 into the bore 50 and are manufactured from metal with a corresponding, higher resistance than the casing body 10, for example, from tempered steel.
The high-pressure pump in Figure 3 is illustrated in accordance with a second exemplary embodiment in which the structure is essentially the same as in the first exemplary embodiment, in addition to which only the following deviating characteristics will be mentioned. In the surface 11 of the casing body 10 facing the casing lid 14a, two separated recesses 160 are thereby inserted whereby a high-pressure well 52 and 54 respectively ends in every recess 160. The recesses 160 respectively display an at least approximately level floor 161 and the port of the high-pressure well 52 and 54 respectively in the respective recess 160 is preferably rounded. Two bores 152, 154 in the casing lid 14a are correspondingly inserted that lead the high-pressure wells 52, 54 to the common high-pressure connector 42. A sealing ring 162 that surrounds the respective high-pressure well 52 and 54 is inserted in every recess 160 in order to seal up the transition from the casing body 10 to the casing lid 14a. In the second exemplary embodiment too, the high-pressure wells 52, 54 thus run without intersections in the casing body 10 and intersections are only present in the casing lid 14a.

Hi U/g. Claims
1. High-pressure pumps, meant particularly for a fuel injection device of an internal combustion engine, with a pump casing (10, 12, 14) in which several pump elements (16) are located, whereby fluid is fed under high pressure through a high-pressure duct system to a common high-pressure connector (42) through the pump elements (16), characterised in that, the pump casing has a casing body (10) and a casing lid (14) for every pump element (16) with the casing lid (14) covering every pump element (16) and being connected to the casing body (10) and that the high-pressure duct system in the casing body (10) displays intersection-free running high-pressure wells (52, 54), which merge in the transition area between the casing body (10) and one of the casing lids (14a) or in one of the casing lids (14a) at a common high-pressure connector (42).
2. High-pressure pumps according to Claim 1, characterised in that, the common high-pressure connector (42) is located at the casing lid (14a).
3. High-pressure pump according to Claim 1 or 2, characterised in that, the high-pressure wells (52, 54) merge in the transition area from the casing body (10) to the casing lid (14a) and end in a recess (60) inserted at a surface (11) facing the casing lid (14a) of the casing body
(10). A single bore (50) proceeds from this recess (60) to the common high-pressure connector (42).
4. High-pressure pump according to Claim 3, characterised in that the floor (61) of the recess (60) is designed to be at least approximately level and that the port of the high-pressure wells (52, 54) is rounded at the floor (61) of the recess (60).
5. High-pressure pump according to Claim 1 or 2, characterised in that, the high-pressure wells (52, 54) respectively end in one of the recesses (160) inserted at the surface (11) facing the casing lid (14a) of the casing body (10), that separated continuations (152, 154) of the high-pressure wells (52, 54) run in the casing lid (14a) and merge in the casing lid (14a) at the common high-pressure connector (42).
6. High-pressure pump according to Claim 5, characterised in that, the floor (161) of the recesses (160) is designed to be at least approximately level and that the ports of the high-pressure wells (52, 54) are respectively round at the floor (161) of the recesses (160).
7. High-pressure pumps according to one of Claims 3 to 6, characterised in that, the a sealing element (62, 162) is inserted in each case in the recess (60) and the recesses (160) respectively to seal the transition from the casing body (10) to the casing lid (14a).
8. High-pressure pumps according to one of the preceding Claims, characterised in that, the casing body (10) is made from a metal of a lower resistance than that of the casing lid (14).
9. High pressure pumps, substantially as hereinabove described and illustrated with reference to the accompanying drawings.